1. Field of the Invention
This invention relates to improvements in door stop alarms, and, more particularly, to improvements in door stop alarms of the type which prevent intrusion and sound an alarm when intrusion is attempted.
2. Description of the Prior Art
In the past, numerous door stops to prevent intrusion have been advanced, many in conjunction with alarms to warn of an entry attempt. For example, U.S. Pat. No. 4,890,092 discloses a wedge shaped door stop that can be inserted beneath a door. The device prevents opening the door and sounds an alarm when an attempt is made to open the door.
U.S. Pat. No. 828,834 shows a portable door engaging stop with toothed and portions to engage the door and the floor, and which are slideably located with respect to each other to close a connection to sound a bell when the door is attempted to be opened.
U.S. Pat. No. 2,870,281 shows a burglar alarm that is connected between the door knob of the door and a nearby floor location, and which has a separate alarm circuit to warn of attempted entry. Similar devices are advanced in U.S. Pat. Nos. 4,607,253; 4,358,758; and 4,442,427.
A number of alarms are provided which have a door engaging lever that is compressed or allowed to spring out to sound an alarm upon opening of the door. Examples of this type of alarm are shown in U.S. Pat. Nos. 2,826,656; 4,193,067; and 4,266,216.
Finally, a portable alarm for entry detection is shown in U.S. Pat. No. 4,264,899 that sounds an alarm when it is tilted to a predetermined extent from its upright position.